1. Field of the Invention
The present invention relates to a coupling element for providing a releasable connection between pipes that convey a fluid under pressure, this element including a pusher and a shutter valve suitable for sliding axially relative to the pusher when coupling the element with a corresponding coupling element. The invention also relates to a coupling incorporating such an element.
2. Description of Related Art
In the field of hydraulic couplings having pushers and shutter valves, it is known to provide sealing for a coupling element when said element is in an uncoupled configuration by means of an O-ring housed at the interface between the pusher and the valve. While the element is being coupled with a corresponding element, the sliding of the valve relative to the pusher positions the sealing O-ring in contact with the fluid flow section in the coupling. With high fluid flow rates, there is therefore a risk of the sealing O-ring being expelled from its housing when the coupling is in the coupled configuration, which can give rise to sealing problems on uncoupling.
EP-A-0 477 949 describes a coupling with pushers and shutter valves in which, in the coupled configuration of the coupling, some of the O-rings that provide sealing between the pushers and the valves in the uncoupled configuration are protected from the fluid flow section by the pusher of one of the elements of the coupling. The above-mentioned O-rings are also used for providing sealing of the coupling in the coupled configuration. For this purpose, those O-rings are designed to be in contact with the pusher that protects them from the fluid flow section in the coupled configuration of the coupling, such that in the event of relative micromovements between the elements of the coupled-together coupling, there is friction at the interface between said O-rings and the protective pusher. Such relative micromovements can occur in particular when the elements of the coupling are locked together not by means of balls, as described in EP-A-0 477 949, but by means of plates carrying multiple connections. The elements of the coupling are then not prevented from moving axially by being in abutment one against the other so as to avoid impeding locking the plates together, so the elements can move towards each other and away from each other axially if, for example, some of the connections carried by the plates are subjected to vibration or convey fluids at different temperatures. The resulting friction at the interface between the O-rings and the protective pusher give rise to deterioration in the quality of the sealing and the lifetime of the O-rings.
U.S. Pat. No. 2,854,259 also describes a coupling having pushers and shutter valves in which, when the coupling is in its coupled configuration, O-rings that provide sealing between the pushers and the valves in the uncoupled configuration are protected from the fluid flow by the pusher of one of the elements of the coupling. While coupling and uncoupling the elements of the coupling, the above-mentioned O-rings are caused to move axially relative to the outer peripheral surface of the protective pusher. The protective pusher is provided with an outside diameter that is smaller than the inside diameter of the O-rings when they are in their rest configuration. Nevertheless, the protective pusher includes orifices in its peripheral surface that are designed to pass a flow of fluid through the coupling in the coupled-together configuration, and at said openings the O-rings are liable to be deformed under the effect of the fluid pressure. In particular, the O-rings are liable to be brought into contact with the edges of the orifices while the elements of the coupling are being coupled together. This gives rise to high levels of friction being exerted on the O-rings each time they go past the orifices in the protective pusher, and thus to premature wear of the O-rings and to deterioration in the quality of sealing.